Topic
Thermal efficiency
About: Thermal efficiency is a research topic. Over the lifetime, 20911 publications have been published within this topic receiving 302373 citations. The topic is also known as: thermodynamic efficiency & efficiency.
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TL;DR: In this paper, six working fluids with zero ozone depletion potential and low global warming potential are used in an organic Rankine cycle (ORC) system to recover waste heat from cylinder jacket water of large marine diesel engines.
85 citations
TL;DR: In this paper, an experimental investigation on heat transfer with porous media inserts during compression and expansion was conducted for a pressure ratio of 10 and 6, respectively, and the results showed that the surface area increase was the predominant cause for the improvement in performance.
85 citations
TL;DR: In this article, the heat transfer and friction characteristics of artificially roughened solar air heaters with different roughness geometries have been reviewed in order to compare the performance of solar air heater having different types of roughness geometry.
Abstract: Solar air heater is an eco-friendly, economical and simple device which is used to harness solar energy for space heating, process heating and agricultural applications. The thermal performance of solar air heater can be improved by the application of artificial roughness on the underside of absorber surface. The heat transfer and friction characteristics of artificially roughened solar air heaters with different roughness geometries have been reviewed in this article. The article presents the authoritative account of the current progress on topic, discusses the previous developments, and throws light on the future directions. An attempt has been made to compare the performance of solar air heater having different types of roughness geometries based on correlations proposed in the literature. Thermo-hydraulic performance parameter (η), thermal efficiency (η th ), thermal efficiency improvement factor (TEIF), effective efficiency (η eff ), and exergetic efficiency (η ex ) are evaluated to gauge the performance of different roughness geometries.
85 citations
TL;DR: In this paper, the authors proposed several novel systems of that type, based on ammonia-water working fluid, which achieved energy and exergy efficiencies of ∼28% and 55-60%, respectively, for the base case studied (at maximum heat input temperature of 450°C).
Abstract: Refrigeration cogeneration systems which generate power alongside with cooling improve energy utilization significantly, because such systems offer a more reasonable arrangement of energy and exergy “flows” within the system, which results in lower fuel consumption as compared to the separate generation of power and cooling or heating. This paper proposes several novel systems of that type, based on ammonia–water working fluid. Importantly, general principles for integration of refrigeration and power systems to produce better energy and exergy efficiencies are summarized, based primarily on the reduction of exergy destruction. The proposed plants analyzed here operate in a fully-integrated combined cycle mode with ammonia–water Rankine cycle(s) and an ammonia refrigeration cycle, interconnected by absorption, separation and heat transfer processes. It was found that the cogeneration systems have good performance, with energy and exergy efficiencies of ∼28% and 55–60%, respectively, for the base-case studied (at maximum heat input temperature of 450 °C). That efficiency is, by itself, excellent for cogeneration cycles using heat sources at these temperatures, with the exergy efficiency comparable to that of nuclear power plants. When using exhaust heat from topping gas turbine power plants, the total plant energy efficiency can rise to the remarkable value of about 57%. The hardware proposed for use is conventional and commercially available; no hardware additional to that needed in conventional power and absorption cycles is needed.
85 citations
TL;DR: In this paper, a Ca looping system that uses CaO as regenerable sorbent to capture CO2 from the flue gases generated in power plants is analyzed, where the CO2 is captured by CaO in a CFB carbonator while coal oxycombustion provides the energy required to regenerate the sorbent.
Abstract: This work analyses a Ca looping system that uses CaO as regenerable sorbent to capture CO2 from the flue gases generated in power plants. The CO2 is captured by CaO in a CFB carbonator while coal oxycombustion provides the energy required to regenerate the sorbent. Part of the energy introduced into the calciner can be transferred to a new supercritical steam cycle to generate additional power. Several case studies have been integrated with this steam cycle. Efficiency penalties, mainly associated with the energy consumption of the ASU, CO2 compressor and auxiliaries, can be as low as 7.5% p. of net efficiency when working with low-CaCO3 make-up flows and integrating the Ca looping with a cement plant that makes use of the spent sorbent. The penalties increase to 8.3% p. when this possibility is not available. Operation conditions aiming at minimum calciner size result in slightly higher-efficiency penalties. © 2010 American Institute of Chemical Engineers AIChE J, 2011
85 citations